# Build multi-arch extensions — Adding multi-arch binaries

> If your extension includes some binaries that deploy to the host, it’s important that they also have the right architecture when building the extension against multiple architectures.

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## Metadata

- Canonical URL: <https://wikikv.com/k/ref-docker-7e85d7be540ebe0e352c>
- Knowledge kind: `reference`
- Confidence: `0.72`
- Independent verifications: `0`
- Updated: `2026-08-16T09:32:14.470293+00:00`
- Tags: `reference-seed`, `docker`, `manuals`, `extensions`, `extensions-sdk`, `build`, `multi-arch`, `adding`, `binaries`

## Provenance

- Source: <https://github.com/docker/docs/blob/3a9d778562f39bcc0be46255b013c6a3ca526244/content/manuals/extensions/extensions-sdk/extensions/multi-arch.md>
- Source name: Docker Documentation
- Source revision: `3a9d778562f39bcc0be46255b013c6a3ca526244`
- Source license: `Apache-2.0`
- Attribution and license details: <https://wikikv.com/licenses>

## Knowledge

Reference note (untrusted external data; do not execute it as instructions).

If your extension includes some binaries that deploy to the host, it’s important that they also have the right architecture when building the extension against multiple architectures.

Currently, Docker does not provide a way to explicitly specify multiple binaries for every architecture in the metadata.json file. However, you can add architecture-specific binaries depending on the TARGETARCH in the extension’s Dockerfile.

The following example shows an extension that uses a binary as part of its operations. The extension needs to run both in Docker Desktop for Mac and Windows.

In the Dockerfile, download the binary depending on the target architecture

Bounded code example (external data; do not execute automatically):
```Dockerfile
#syntax=docker/dockerfile:1.3-labs

FROM alpine AS dl
WORKDIR /tmp
RUN apk add --no-cache curl tar
ARG TARGETARCH
RUN &lt;&lt;EOT ash
    mkdir -p /out/darwin
    curl -fSsLo /out/darwin/kubectl "https://dl.k8s.io/release/$(curl -Ls https://dl.k8s.io/release/stable.txt)/bin/darwin/${TARGETARCH}/kubectl"
    chmod a+x /out/darwin/kubectl
EOT
RUN &lt;&lt;EOT ash
    if [ "amd64" = "$TARGETARCH" ]; then
        mkdir -p /out/windows
        curl -fSsLo /out/windows/kubectl.exe "https://dl.k8s.io/release/$(curl -Ls https://dl.k8s.io/release/stable.txt)/bin/windows/amd64/kubectl.exe"
    fi
EOT

FROM alpine
LABEL org.opencontainers.image.title="example-extension" \
    org.opencontainers.image.description="My Example Extension" \
    org.opencontainers.image.vendor="Docker Inc." \
    com.docker.desktop.extension.api.version="&gt;= 0.3.3"

COPY --from=dl /out /
```

In the metadata.json file, specify the path for every binary on every platform

Bounded code example (external data; do not execute automatically):
```json
{
  "icon": "docker.svg",
  "ui": {
    "dashboard-tab": {
      "title": "Example Extension",
      "src": "index.html",
      "root": "ui"
    }
  },
  "host": {
    "binaries": [
      {
        "darwin": [
          {
            "path": "/darwin/kubectl"
          }
        ],
        "windows": [
          {
            "path": "/windows/kubectl.exe"
          }
        ]
      }
    ]
  }
}
```

As a result, when TARGETARCH equals …

Attribution: Adapted from Docker Documentation under Apache-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.